The field of the invention generally relates to electronic circuit boards, and more particularly, to systems and apparatus for controlling electrostatic discharge on electronic circuit boards.
Electronic systems generally utilize electronic devices such as circuit boards, including printed circuit boards (PCBs), to interconnect electronic components including, for example, semiconductors, microprocessors, resistors, transistors, diodes, lights, and various other electronic components. Many electronic components, including semiconductor devices like microprocessors and integrated circuits, are susceptible to being permanently damaged by electrostatic discharge (ESD) which can subject nearby objects to very high electrical voltage and current. Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. A buildup of static electricity can be caused by tribocharging, or by electrostatic induction. Tribocharging is the build-up of static electric charges caused by friction between two materials. For instance, a human body can accumulate an electrostatic charge by walking on a rug, and rubber or plastic objects can build-up charges by rubbing them against a sweater or other types of fabric. The ESD occurs when the charged object contacts or comes sufficiently close to a differently charged object.
If a static charge discharges to an electronic device, the large voltage and current can permanently damage electronic components of the device. For instance, the voltage of an ESD is typically significantly higher than the breakdown voltage of many semiconductor devices like microprocessors and integrated circuits. If the semiconductor device is subjected to voltage exceeding the breakdown voltage, the semiconductor device is often permanently damaged and rendered inoperable.
Accordingly, a number of protective devices have been previously disclosed to protect electronic devices from being damaged by ESD. As an example, transient voltage suppression diodes (TVS diodes) have been utilized in the design and manufacture of electronic devices to protect the components from being damaged by ESD. The TVS diodes typically serve as parallel protection elements which divert transient current away from protected components in the event of an ESD. However, there are many different types of TVS diodes with different specifications, and they must be designed into the circuit design of the electronic devices.